One consequence could be the emergence of new power structures. Those who can harness the returning magic might gain political or social influence. For example, a group of young wizards could form a new council to oversee the use of magic. Another consequence is the change in the natural environment. Magical creatures might return, like unicorns and dragons, which could disrupt the existing ecosystem. Also, the cultural identity of Britain in the novel would be transformed as magic becomes an integral part of daily life, with new festivals and traditions related to magic emerging.
Magic could return to Britain in the fantasy novel because of a shift in the magical ley lines. These are like energy channels for magic in the world of fantasy. If there is a significant cosmological event, such as an alignment of stars or a change in the flow of magical energy from other dimensions, it might cause the ley lines in Britain to start flowing with magic again. This would lead to the return of magic in various forms, from the ability of people to perform spells to the appearance of magical creatures that were once thought extinct.
In some fictions, not returning a book might lead to a fine. For example, in a story set in a strict library system in a magical world, if you don't return the book on time, you could be magically locked out of all libraries. It could also damage your reputation among the librarian community, who might spread the word and make it difficult for you to borrow books in the future.
There could be personal consequences for Harry as well. He might face opposition and even threats from those who want to protect the status quo in Magical Britain. His friends and family could also be affected, either by being targeted or by being caught in the middle of the conflict between Harry and the establishment. However, this could also make him more determined to fight for what he believes is right.
It should have unique and imaginative magic systems. Also, the characters and their development need to be compelling and stand out.
Well, usually it leads to chaos and unexpected problems for the characters. Sometimes it even puts them in serious danger.
One possible consequence could be that the healer accidentally harms the patient instead of curing them. For example, if the magic is misdirected, it might cause internal damage or make the illness worse.
He might avoid any events or communities related to magic fanfic. He won't be interested in reading or discussing them.
Using black magic for revenge in comics often leads to dire outcomes. The characters might face supernatural punishments or moral condemnation.
For America in fantasy novels, a common trope is the underdog hero who overcomes great odds. It could be a young farmer's son who discovers he has magic powers and goes on to save the world. In contrast, for Britain, a trope is the noble knight or wizard from an ancient family. They are often tasked with protecting some ancient relic or secret.